if you have someone with behemoth then try to use it too.
having more kami with cure debuff is nice, but if all of them get pertrified then no one can cure them, while you can use the eidolon as long as the main isn't beaten.
my first battle video i recorded was against medusa, ofc no ragnarok back then and i was weak either way so i recorded unltimate run.
back then i had no idea about weapon skill and stuff+ barely had any light kami but managed to win against her :O
it's not ragnarok, but maybe watching a battle, even if ultimate, will help somehow :O